Search Results: "ema"

7 January 2025

Jonathan Wiltshire: Using TPM for Automatic Disk Decryption in Debian 12

These days it s straightforward to have reasonably secure, automatic decryption of your root filesystem at boot time on Debian 12. Here s how I did it on an existing system which already had a stock kernel, secure boot enabled, grub2 and an encrypted root filesystem with the passphrase in key slot 0. There s no need to switch to systemd-boot for this setup but you will use systemd-cryptenroll to manage the TPM-sealed key. If that offends you, there are other ways of doing this.

Caveat The parameters I ll seal a key against in the TPM include a hash of the initial ramdisk. This is essential to prevent an attacker from swapping the image for one which discloses the key. However, it also means the key has to be re-sealed every time the image is rebuilt. This can be frequent, for example when installing/upgrading/removing packages which include a kernel module. You won t get locked out (as long as you still have a passphrase in another slot), but will need to re-seal the key to restore the automation. You can also choose not to include this parameter for the seal, but that opens the door to such an attack.

Caution: these are the steps I took on my own system. You may need to adjust them to avoid ending up with a non-booting system.

Check for a usable TPM device We ll bind the secure boot state, kernel parameters, and other boot measurements to a decryption key. Then, we ll seal it using the TPM. This prevents the disk being moved to another system, the boot chain being tampered with and various other attacks.
# apt install tpm2-tools
# systemd-cryptenroll --tpm2-device list
PATH        DEVICE     DRIVER 
/dev/tpmrm0 STM0125:00 tpm_tis

Clean up older kernels including leftover configurations I found that previously-removed (but not purged) kernel packages sometimes cause dracut to try installing files to the wrong paths. Identify them with:
# apt install aptitude
# aptitude search '~c'
Change search to purge or be more selective, this part is an exercise for the reader.

Switch to dracut for initramfs images Unless you have a particular requirement for the default initramfs-tools, replace it with dracut and customise:
# mkdir /etc/dracut.conf.d
# echo 'add_dracutmodules+=" tpm2-tss crypt "' > /etc/dracut.conf.d/crypt.conf
# apt install dracut

Remove root device from crypttab, configure grub Remove (or comment) the root device from /etc/crypttab and rebuild the initial ramdisk with dracut -f. Edit /etc/default/grub and add rd.auto rd.luks=1 to GRUB_CMDLINE_LINUX. Re-generate the config with update-grub. At this point it s a good idea to sanity-check the initrd contents with lsinitrd. Then, reboot using the new image to ensure there are no issues. This will also have up-to-date TPM measurements ready for the next step.

Identify device and seal a decryption key
# lsblk -ip -o NAME,TYPE,MOUNTPOINTS
NAME                                                    TYPE  MOUNTPOINTS
/dev/nvme0n1p4                                          part  /boot
/dev/nvme0n1p5                                          part  
 -/dev/mapper/luks-deff56a9-8f00-4337-b34a-0dcda772e326 crypt 
   -/dev/mapper/lv-var                                  lvm   /var
   -/dev/mapper/lv-root                                 lvm   /
   -/dev/mapper/lv-home                                 lvm   /home
In this example my root filesystem is in a container on /dev/nvme0n1p5. The existing passphrase key is in slot 0.
# systemd-cryptenroll --tpm2-device=auto --tpm2-pcrs=7+8+9+14 /dev/nvme0n1p5
Please enter current passphrase for disk /dev/nvme0n1p5: ********
New TPM2 token enrolled as key slot 1.
The PCRs I chose (7, 8, 9 and 14) correspond to the secure boot policy, kernel command line (to prevent init=/bin/bash-style attacks), files read by grub including that crucial initrd measurement, and secure boot MOK certificates and hashes. You could also include PCR 5 for the partition table state, and any others appropriate for your setup.

Reboot You should now be able to reboot and the root device will be unlocked automatically, provided the secure boot measurements remain consistent. The key slot protected by a passphrase (mine is slot 0) is now your recovery key. Do not remove it!
Please consider supporting my work in Debian and elsewhere through Liberapay.

Thorsten Alteholz: My Debian Activities in December 2024

Debian LTS This was my hundred-twenty-sixth month that I did some work for the Debian LTS initiative, started by Raphael Hertzog at Freexian. I worked on updates for ffmpeg and haproxy in all releases. Along the way I marked more CVEs as not-affected than I had to fix. So finally there was no upload needed for haproxy anymore. Unfortunately testing ffmpeg was not as easy, as the recommended just look whether mpv can play random videos is not really satisfying. So the upload will happen only in January. I also wonder whether fixing glewlwyd is really worth the effort, as the software is already EOL upstream. Debian ELTS This month was the seventy-seventhth ELTS month. During my allocated time I worked on ffmpeg, haproxy, amanda and kmail-account-wizzard. Like LTS, all CVEs of haproxy and some of ffmpeg could be marked as not-affected and testing of the other packages was/is not really straight forward. So the final upload will only happen in January as well. Debian Printing Unfortunately I didn t found any time to work on this topic. Debian Matomo Thanks a lot to William Desportes for all fixes of my bad PHP packaging. Debian Astro This month I uploaded new packages or new upstream or bugfix versions of: I again sponsored an upload of calceph. Debian IoT This month I uploaded new upstream or bugfix versions of: Debian Mobcom This month I uploaded new packages or new upstream or bugfix versions of: misc This month I uploaded new upstream or bugfix versions of: I also sponsored uploads of emacs-lsp-docker, emacs-dape, emacs-oauth2, gpgmngr, libjs-jush. FTP master This month I accepted 330 and rejected 13 packages. The overall number of packages that got accepted was 335.

Enrico Zini: Debugging printing to a remote printer

I upgraded to Debian testing/trixie, and my network printer stopped appearing in print dialogs. These are notes from the debugging session. Check firewall configuration I tried out kde, which installed plasma-firewall, which installed firewalld, which closed by default the ports used for printing. For extra fun, appindicators are not working in Gnome and so firewall-applet is currently useless, although one can run firewall-config manually, or use the command line that might be more user friendly than the UI. Step 1: change the zone for the home wifi to "Home":
firewall-cmd  --zone home --list-interfaces
firewall-cmd  --zone home --add-interface wlp1s0
Step 2: make sure the home zone can print:
firewall-cmd --zone home --list-services
firewall-cmd --zone home --add-service=ipp
firewall-cmd --zone home --add-service=ipp-client
firewall-cmd --zone home --add-service=mdns
I searched and searched but I could not find out whether ipp is needed, ipp-client is needed, or both are needed. Check if avahi can see the printer Is the printer advertised correctly over mdns? When it didn't work:
$ avahi-browse -avrt
= wlp1s0 IPv6 Brother HL-2030 series @ server                UNIX Printer         local
   hostname = [server.local]
   address = [...ipv6 address...]
   port = [0]
   txt = []
= wlp1s0 IPv4 Brother HL-2030 series @ server                UNIX Printer         local
   hostname = [server.local]
   address = [...ipv4 address...]
   port = [0]
   txt = []
$ avahi-browse -rt _ipp._tcp
[empty]
When it works:
$ avahi-browse -avrt
= wlp1s0 IPv6 Brother HL-2030 series @ server                Secure Internet Printer local
   hostname = [server.local]
   address = [...ipv6 address...]
   port = [631]
   txt = ["printer-type=0x1046" "printer-state=3" "Copies=T" "TLS=1.2" "UUID= " "URF=DM3" "pdl=application/octet-stream,application/pdf,application/postscript,image/jpeg,image/png,image/pwg-raster,image/urf" "product=(HL-2030 series)" "priority=0" "note=" "adminurl=https://server.local.:631/printers/Brother_HL-2030_series" "ty=Brother HL-2030 series, using brlaser v6" "rp=printers/Brother_HL-2030_series" "qtotal=1" "txtvers=1"]
= wlp1s0 IPv6 Brother HL-2030 series @ server                UNIX Printer         local
   hostname = [server.local]
   address = [...ipv6 address...]
   port = [0]
   txt = []
= wlp1s0 IPv4 Brother HL-2030 series @ server                Secure Internet Printer local
   hostname = [server.local]
   address = [...ipv4 address...]
   port = [631]
   txt = ["printer-type=0x1046" "printer-state=3" "Copies=T" "TLS=1.2" "UUID= " "URF=DM3" "pdl=application/octet-stream,application/pdf,application/postscript,image/jpeg,image/png,image/pwg-raster,image/urf" "product=(HL-2030 series)" "priority=0" "note=" "adminurl=https://server.local.:631/printers/Brother_HL-2030_series" "ty=Brother HL-2030 series, using brlaser v6" "rp=printers/Brother_HL-2030_series" "qtotal=1" "txtvers=1"]
= wlp1s0 IPv4 Brother HL-2030 series @ server                UNIX Printer         local
   hostname = [server.local]
   address = [...ipv4 address...]
   port = [0]
   txt = []
$ avahi-browse -rt _ipp._tcp
+ wlp1s0 IPv6 Brother HL-2030 series @ server                Internet Printer     local
+ wlp1s0 IPv4 Brother HL-2030 series @ server                Internet Printer     local
= wlp1s0 IPv4 Brother HL-2030 series @ server                Internet Printer     local
   hostname = [server.local]
   address = [...ipv4 address...]
   port = [631]
   txt = ["printer-type=0x1046" "printer-state=3" "Copies=T" "TLS=1.2" "UUID= " "URF=DM3" "pdl=application/octet-stream,application/pdf,application/postscript,image/jpeg,image/png,image/pwg-raster,image/urf" "product=(HL-2030 series)" "priority=0" "note=" "adminurl=https://server.local.:631/printers/Brother_HL-2030_series" "ty=Brother HL-2030 series, using brlaser v6" "rp=printers/Brother_HL-2030_series" "qtotal=1" "txtvers=1"]
= wlp1s0 IPv6 Brother HL-2030 series @ server                Internet Printer     local
   hostname = [server.local]https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1092109
   address = [...ipv6 address...]
   port = [631]
   txt = ["printer-type=0x1046" "printer-state=3" "Copies=T" "TLS=1.2" "UUID= " "URF=DM3" "pdl=application/octet-stream,application/pdf,application/postscript,image/jpeg,image/png,image/pwg-raster,image/urf" "product=(HL-2030 series)" "priority=0" "note=" "adminurl=https://server.local.:631/printers/Brother_HL-2030_series" "ty=Brother HL-2030 series, using brlaser v6" "rp=printers/Brother_HL-2030_series" "qtotal=1" "txtvers=1"]
Check if cups can see the printer From CUPS' Using Network Printers:
$ /usr/sbin/lpinfo --include-schemes dnssd -v
network dnssd://Brother%20HL-2030%20series%20%40%20server._ipp._tcp.local/cups?uuid= 
Debugging session interrupted At this point, the printer appeared. It could be that: In the end, debugging failed successfully, and this log now remains as a reference for possible further issues.

3 January 2025

Bits from Debian: Bits from the DPL

Dear Debian community, this is bits from DPL for December. Happy New Year 2025! Wishing everyone health, productivity, and a successful Debian release later in this year. Strict ownership of packages I'm glad my last bits sparked discussions about barriers between packages and contributors, summarized temporarily in some post on the debian-devel list. As one participant aptly put it, we need a way to visibly say, "I'll do the job until someone else steps up". Based on my experience with the Bug of the Day initiative, simplifying the process for engaging with packages would significantly help. Currently we have
  1. NMU The Developers Reference outlines several preconditions for NMUs, explicitly stating, "Fixing cosmetic issues or changing the packaging style in NMUs is discouraged." This makes NMUs unsuitable for addressing package smells. However, I've seen NMUs used for tasks like switching to source format 3.0 or bumping the debhelper compat level. While it's technically possible to file a bug and then address it in an NMU, the process inherently limits the NMUer's flexibility to reduce package smells.
  2. Package Salvaging This is another approach for working on someone else's packages, aligning with the process we often follow in the Bug of the Day initiative. The criteria for selecting packages typically indicate that the maintainer either lacks time to address open bugs, has lost interest, or is generally MIA.
Both options have drawbacks, so I'd welcome continued discussion on criteria for lowering the barriers to moving packages to Salsa and modernizing their packaging. These steps could enhance Debian overall and are generally welcomed by active maintainers. The discussion also highlighted that packages on Salsa are often maintained collaboratively, fostering the team-oriented atmosphere already established in several Debian teams. Salsa Continuous Integration As part of the ongoing discussion about package maintenance, I'm considering the suggestion to switch from the current opt-in model for Salsa CI to an opt-out approach. While I fully agree that human verification is necessary when the pipeline is activated, I believe the current option to enable CI is less visible than it should be. I'd welcome a more straightforward approach to improve access to better testing for what we push to Salsa. Number of packages not on Salsa In my campaign, I stated that I aimed to reduce the number of packages maintained outside Salsa to below 2,000. As of March 28, 2024, the count was 2,368. As of this writing, the count stands at 1,928 [1], so I consider this promise fulfilled. My thanks go out to everyone who contributed to this effort. Moving forward, I'd like to set a more ambitious goal for the remainder of my term and hope we can reduce the number to below 1,800. [1] UDD query: SELECT DISTINCT count(*) FROM sources WHERE release = 'sid' and vcs_url not like '%salsa%' ; Past and future events Talk at MRI Together In early December, I gave a short online talk, primarily focusing on my work with the Debian Med team. I also used my position as DPL to advocate for attracting more users and developers from the scientific research community. FOSSASIA I originally planned to attend FOSDEM this year. However, given the strong Debian presence there and the need for better representation at the FOSSASIA Summit, I decided to prioritize the latter. This aligns with my goal of improving geographic diversity. I also look forward to opportunities for inter-distribution discussions. Debian team sprints Debian Ruby Sprint I approved the budget for the Debian Ruby Sprint, scheduled for January 2025 in Paris. If you're interested in contributing to the Ruby team, whether in person or online, consider reaching out to them. I'm sure any helping hand would be appreciated. Debian Med sprint There will also be a Debian Med sprint in Berlin in mid-February. As usual, you don't need to be an expert in biology or medicine basic bug squashing skills are enough to contribute and enjoy the friendly atmosphere the Debian Med team fosters at their sprints. For those working in biology and medicine, we typically offer packaging support. Anyone interested in spending a weekend focused on impactful scientific work with Debian is warmly invited. Again all the best for 2025
Andreas.

2 January 2025

Martin-Éric Racine: On the future of i386 on Debian

Before we proceed, let's emphasize a few things: This being said, I still think that the current approach of keeping i386 among the supported architectures, all while no longer shipping kernels, is entirely the wrong decision. What should instead be done is to keep on shipping i386 kernels for Trixie, but clearly indicate in the Trixie Release Notes that i386 is supported for the last time and thereafter fully demoted to Ports.

Colin Watson: Free software activity in December 2024

Most of my Debian contributions this month were sponsored by Freexian, as well as one direct donation via Liberapay (thanks!). OpenSSH I issued a bookworm update with a number of fixes that had accumulated over the last year, especially fixing GSS-API key exchange which was quite broken in bookworm. base-passwd A few months ago, the adduser maintainer started a discussion with me (as the base-passwd maintainer) and the shadow maintainer about bringing all three source packages under one team, since they often need to cooperate on things like user and group names. I agreed, but hadn t got round to doing anything about it until recently. I ve now officially moved it under team maintenance. debconf Gioele Barabucci has been working on eliminating duplicated code between debconf and cdebconf, ultimately with the goal of migrating to cdebconf (which I m not sure I m convinced of as a goal, but if we can make improvements to both packages as part of working towards it then there s no harm in that). I finally got round to reviewing and merging confmodule changes in each of debconf and cdebconf. This caused an installer regression due to a weirdness in cdebconf-udeb s packaging, which I fixed - sorry about that! I ve also been dealing with a few patch submissions that had been in my queue for a long time, but more on that next month if all goes well. CI issues I noticed and fixed a problem with Restrictions: needs-sudo in autopkgtest. I fixed broken aptly images in the Salsa CI pipeline. Python team Last month, I mentioned some progress on sorting out the multipart vs. python-multipart name conflict in Debian (#1085728), and said that I thought we d be able to finish it soon. I was right! We got it all done this month: The Python 3.13 transition continues, and last month we were able to add it to the supported Python versions in testing. (The next step will be to make it the default.) I fixed lots of problems in aid of this, including: Sphinx 8.0 removed some old intersphinx_mapping syntax which turned out to still be in use by many packages in Debian. The fixes for this were individually trivial, but there were a lot of them: I found that twisted 24.11.0 broke tests in buildbot and wokkel, and fixed those. I packaged python-flatdict, needed for a new upstream version of python-semantic-release. I tracked down a test failure in vdirsyncer (which I ve been using for some years, but had never previously needed to modify) and contributed a fix upstream. I fixed some packages to tolerate future versions of dh-python that will drop their dependency on python3-setuptools: I fixed django-cte to remove a build-dependency on the obsolete python3-nose package. I added Django 5.1 support to django-polymorphic. (There are a number of other packages that still need work here.) I fixed various other build/test failures: I upgraded these packages to new upstream versions: I updated the team s library style guide to remove material related to Python 2 and early versions of Python 3, which is no longer relevant to any current Python packaging work. Other Python upstream work I happened to notice a Twisted upstream issue requesting the removal of the deprecated twisted.internet.defer.returnValue, realized it was still used in many places in Debian, and went on a PR-filing spree informed by codesearch to try to reduce the future impact of such a change on Debian: Other small fixes Santiago Vila has been building the archive with make --shuffle (also see its author s explanation). I fixed associated bugs in cccc (contributed upstream), groff, and spectemu. I backported an upstream patch to putty to fix undefined behaviour that affected use of the small keypad . I removed groff s Recommends: libpaper1 (#1091375, #1091376), since it isn t currently all that useful and was getting in the way of a transition to libpaper2. I filed an upstream bug suggesting better integration in this area.

1 January 2025

Tim Retout: Strauss as Pop Music

While watching the Vienna New Year s Concert today, reading about its perhaps somewhat problematic origins, I was struck by the observation that the Strauss family s polkas were seen as pop music during their lifetime, not as serious as proper classical composers, and so it took some time before the Vienna Philharmonic would actually play their work. (Perhaps the space-themed interval today and the ballet dancers pretending to be a steam train were a continuation of the true spirit of this? It felt very Eurovision.) I can t decide if it s remarkable that this year was the first time a female composer (Constanze Geiger) was represented at this concert, or if that is what you get when you set up a tradition of playing mainly Strauss?

Russ Allbery: 2024 Book Reading in Review

In 2024, I finished and reviewed 46 books, not counting another three books I've finished but not yet reviewed and which will therefore roll over to 2025. This is slightly fewer books than the last couple of years, but more books than 2021. Reading was particularly spotty this year, with much of the year's reading packed into late November and December. This was a year in which I figured out I was trying to do too much, but did not finish figuring out what to do about it. Reading and particularly reviewing reflected that, with long silent periods and then attempts to catch up. One of the goals for next year is to find a more sustainable balance for the hobbies in my life, including reading. My favorite books I read this year were Ashley Herring Blake's Bright Falls sapphic romance trilogy: Delilah Green Doesn't Care, Astrid Parker Doesn't Fail, and Iris Kelly Doesn't Date. These are not perfect books, but they made me laugh, made me cry, and were impossible to put down. My thanks to a video from BookTuber Georgia Marie for the recommendation. I Shall Wear Midnight was the best of the remaining Pratchett novels. It's the penultimate Tiffany Aching book and, in my opinion, the best. All of the elements of the previous books come together in snarky competence porn that was a delight to read. The best book I read last year was Mark Lawrence's The Book That Wouldn't Burn, which much to my surprise did not make a single award list for its publication year of 2023. It was a tour de force of world-building that surprised me multiple times. Unfortunately, the sequel was not as good and I fear the series may be heading in the wrong direction. I am attempting to stay hopeful about the upcoming third and concluding book. I didn't read much non-fiction this year, but the best of what I did read was Zeke Faux's Number Go Up about the cryptocurrency bubble. This book will not change anyone's mind, but it's a readable and entertaining summary of some of the more obvious cryptocurrency scams. I also had enough quibbles with it to write an extended review, which is a compliment of sorts. The Discworld read-through is done, so I may either start or return to another series re-read in 2025. I have a huge backlog of all sorts of books, though, so we will see how the year goes. As always, I have no specific numeric goals, just a hope that I can make time for regular and varied reading and maintain a rhythm with writing reviews. The full analysis includes some additional personal reading statistics, probably only of interest to me.

Louis-Philippe V ronneau: 2024 A Musical Retrospective

Another musical retrospective. If you enjoy this, I also did a 2022 and a 2023 one. Albums In 2024, I added 88 new albums to my collection that's a lot! This year again, I bought the vast majority of my music on Bandcamp. To be honest, I'm quite distraught by what's become of that website. Although it stays a wonderful place to buy underground music, Songtradr, the new owner of the platform, has been shown to be viciously anti-union. Money continues to ruin the world, I guess. Concerts I continued to go to a lot of concerts in 2024 (25!). Over the past 3 years, I have been going to more and more concerts, and I think I've reached my "peak". A mean of a concert every two weeks is quite a lot :) If you also like music and concerts, but find yourself not going to as many as you would like, the real secret is not to be afraid to go to concerts alone. Going with friends is always fun, but if I restricted myself to only going to concerts in a group, I'd barely see a few each year. Another good advice is to bring a book or something else1 to pass the time between sets. It can often take 30-45 minutes between sets for the artists to get their instruments ready, which can get quite boring if you just stand there and wait. Anyway, here are the concerts I went to in 2024: Shout out to the Gancio project and to the folks running the Montreal instance. It continues to be a smash hit and most of the interesting concerts end up being advertised there. See you all in 2025!

  1. I bought a Miyoo Mini Plus, a handheld Linux console running OnionOS, for that express reason. So far it's been great and I've been very happy to revisit some childhood classics.

31 December 2024

Chris Lamb: Favourites of 2024

Here are my favourite books and movies that I read and watched throughout 2024. It wasn't quite the stellar year for books as previous years: few of those books that make you want to recommend and/or buy them for all your friends. In subconscious compensation, perhaps, I reread a few classics (e.g. True Grit, Solaris), and I'm almost finished my second read of War and Peace.

Books

Elif Batuman: Either/Or (2022) Stella Gibbons: Cold Comfort Farm (1932) Michel Faber: Under The Skin (2000) Wallace Stegner: Crossing to Safety (1987) Gustave Flaubert: Madame Bovary (1857) Rachel Cusk: Outline (2014) Sara Gran: The Book of the Most Precious Substance (2022) Anonymous: The Railway Traveller s Handy Book (1862) Natalie Hodges: Uncommon Measure: A Journey Through Music, Performance, and the Science of Time (2022)Gary K. Wolf: Who Censored Roger Rabbit? (1981)

Films Recent releases

Seen at a 2023 festival. Disappointments this year included Blitz (Steve McQueen), Love Lies Bleeding (Rose Glass), The Room Next Door (Pedro Almod var) and Emilia P rez (Jacques Audiard), whilst the worst new film this year was likely The Substance (Coralie Fargeat), followed by Megalopolis (Francis Ford Coppola), Unfrosted (Jerry Seinfeld) and Joker: Folie Deux (Todd Phillips).
Older releases ie. Films released before 2023, and not including rewatches from previous years. Distinctly unenjoyable watches included The Island of Dr. Moreau (John Frankenheimer, 1996), Southland Tales (Richard Kelly, 2006), Any Given Sunday (Oliver Stone, 1999) & The Hairdresser s Husband (Patrice Leconte, 19990). On the other hand, unforgettable cinema experiences this year included big-screen rewatches of Solaris (Andrei Tarkovsky, 1972), Blade Runner (Ridley Scott, 1982), Apocalypse Now (Francis Ford Coppola, 1979) and Die Hard (John McTiernan, 1988).

Russ Allbery: Review: Metal from Heaven

Review: Metal from Heaven, by August Clarke
Publisher: Erewhon
Copyright: November 2024
ISBN: 1-64566-099-0
Format: Kindle
Pages: 443
Metal from Heaven is industrial-era secondary-world fantasy with a literary bent. It is a complete story in one book, and I would be very surprised by a sequel. Clarke previously wrote the Scapegracers young-adult trilogy, which got excellent reviews and a few award nominations, as H.A. Clarke. This is his first adult novel.
Know I adore you. Look out over the glow. The cities sundered, their machines inverted, mountains split and prairies blazing, that long foreseen Hereafter crowning fast. This calamity is a promise made to you. A prayer to you, and to your shadow which has become my second self, tucked behind my eye and growing in tandem with me, pressing outwards through the pupil, the smarter, truer, almost bursting reason for our wrath. Do not doubt me. Just look. Watch us rise as the sun comes up over the beauty. The future stains the bleakness so pink. When my violence subsides, we will have nothing, and be champions.
Marney Honeycutt is twelve years old, a factory worker, and lustertouched. She works in the Yann I. Chauncey Ichorite Foundry in Ignavia City, alongside her family and her best friend, shaping the magical metal ichorite into the valuable industrial products of a new age of commerce and industry. She is the oldest of the lustertouched, the children born to factory workers and poisoned by the metal. It has made her allergic, prone to fits at any contact with ichorite, but also able to exert a strange control over the metal if she's willing to pay the price of spasms and hallucinations for hours afterwards. As Metal from Heaven opens, the workers have declared a strike. Her older sister is the spokesperson, demanding shorter hours, safer working conditions, and an investigation into the health of the lustertouched children. Chauncey's response is to send enforcer snipers to kill the workers, including the entirety of her family.
The girl sang, "Unalone toward dawn we go, toward the glory of the new morning." An enforcer shot her in the belly, and when she did not fall, her head.
Marney survives, fleeing into the city, swearing an impossible personal revenge against Yann Chauncey. An act of charity gets her a ticket on a train into the countryside. The woman who bought her ticket is a bandit who is on the train to rob it. Marney's ability to control ichorite allows her to help the bandits in return, winning her a place with the Highwayman's Choir who have been preying on the shipments of the rich and powerful and then disappearing into the hills. The Choir's secret is that the agoraphobic and paranoid Baron of the Fingerbluffs is dead and has been for years. He was killed by his staff, Hereafterist idealists, who have turned his remote territory into an anarchist commune and haven for pirates and bandits. This becomes Marney's home and the Choir becomes her family, but she never forgets her oath of revenge or the childhood friend she left behind in the piles of bodies and to whom this story is narrated. First, Clarke's writing is absolutely gorgeous.
We scaled the viny mountain jags at Montrose Barony's legal edge, the place where land was and wasn't Ignavia, Royston, and Drustland alike. There was a border but it was diffuse and hallucinatory, even more so than most. On legal papers and state maps there were harsh lines that squashed topography and sanded down the mountains into even hills in planter's rows, but here among the jutting rocks and craggy heather, the ground was lineless.
The rhythm of it, the grasp of contrast and metaphor, the word choice! That climactic word "lineless," with its echo of limitless. So good. Second, this is the rarest of books: a political fantasy that takes class and religion seriously and uses them for more than plot drivers. This is not at all our world, and the technology level is somewhat ambiguous, but the parallels to the Gilded Age and Progressive Era are unmistakable. The Hereafterists that Marney joins are political anarchists, not in the sense of alternative governance structures and political theory sanitized for middle-class liberals, but in the sense of Emma Goldman and Peter Kropotkin. The society they have built in the Fingerbluffs is temporary, threatened, and contingent, but it is sincere and wildly popular among the people who already lived there. Even beyond politics, class is a tangible force in this book. Marney is a factory worker and the child of factory workers. She barely knows how to read and doesn't magically learn over the course of the book. She has friends who are clever in the sense rewarded by politics and nobility, who navigate bureaucracies and political nuance, but that is not Marney's world. When, towards the end of the book, she has to deal with a gathering of high-class women, the contrast is stark, and she navigates that gathering only by being entirely unexpected. Perhaps the best illustration of the subtlety of this is the terminology in the book for lesbian. Marney is a crawly, which is a slur thrown at people like her (and one of the rare fictional slurs that work exactly as the author intended) but is also simply what she calls herself. Whether or not it functions as a slur depends on context, and the context is never hard to understand. The high-class lesbians she meets later are Lunarists, and react to crawly as a vile and insulting word. They use language to separate themselves from both the insult and from the social class that uses it. Language is an indication of culture and manners and therefore of morality, unlike deeds, which admit endless justifications.
Conversation was fleeting. Perdita managed with whomever stood near her, chipper about every prettiness she saw, the flitting butterflies, the dappled light between the leaves, the lushness and the fragrance of untamed land, and her walking companions took turns sharing in her delight. It was infectious, how happy she was. She was going to slaughter millions. She was going to skip like this all the while.
The handling of religion is perhaps even better. Marney was raised a Tullian, which sits alongside two other fleshed-out fictional religions and sketches of several more. Tullians tend to be conservative and patriarchal, and Marney has a realistically complicated relationship with faith: sticking with some Tullian worship practices and gestures because they're part of who she is, feeling a kinship to other Tullians, discarding beliefs that don't fit her, and revising others. Every major religion has a Hereafterist spin or reinterpretation that upends or reverses the parts of the religion that were used to prop up the existing social order and brings it more in line with Hereafterist ideals. We see the Tullian Hereafterist variation in detail, and as someone who has studied a lot of methods of reinterpreting Christianity, I was impressed by how well Clarke invents both a belief system and its revisionist rewrite. This is exactly how religions work in human history, but one almost never sees this subtlety in fantasy novels. Marney's allergy to ichorite causes her internal dialogue to dissolve into hallucinatory synesthesia when she's manipulating or exposed to it. Since that's most of the book, substantial portions read like drug trips with growing body horror. I normally hate this type of narration, so it's a sign of just how good Clarke's writing is that I tolerated it and even enjoyed parts. It helps that the descriptions are irreverent and often surprising, full of unexpected metaphors and sudden turns. It's very hard not to quote paragraph after paragraph of this book. Clarke is also doing a lot with gender that I don't feel qualified to comment in detail on, but it would not surprise me to see this book in the Otherwise Award recommendation list. I can think of three significant male characters, all of whom are well-done, but every other major character is female by at least some gender definition. Within that group, though, is huge gender diversity of the complicated and personal type that doesn't force people into defined boxes. Marney's sexuality is similarly unclassified and sometimes surprising. My one complaint is that I thought the sex scenes (which, to warn, are often graphic) fell into the literary fiction trap of being described so closely and physically that it didn't feel like anyone involved was actually enjoying themselves. (This is almost certainly a matter of personal taste.) I had absolutely no idea how Clarke was going to end this book, and the last couple of chapters caught me by surprise. I'm still not sure what I think about the climax. It's not the ending that I wanted, but one of the merits of this book is that it never did what I thought I wanted and yet made me enjoy the journey anyway. It is, at least, a genre ending, not a literary ending: The reader gets a full explanation of what is going on, and the setting is not static the way that it so often is in literary fiction. The characters can change the world, for good or for ill. The story felt frustrating and incomplete when I first finished it, but I haven't stopped thinking about this book and I think I like the shape of it a bit more now. It was certainly unexpected, at least by me. Clarke names Dhalgren as one of their influences in the acknowledgments, and yes, Metal from Heaven is that kind of book. This is the first 2024 novel I've read that felt like the kind of book that should be on award shortlists. I'm not sure it was entirely successful, and there are parts of it that I didn't like or that weren't for me, but it's trying to do something different and challenging and uncomfortable, and I think it mostly worked. And the writing is so good.
She looked like a mythic princess from the old woodcuts, who ruled nature by force of goodness and faith and had no legal power.
Metal from Heaven is not going to be everyone's taste. If you do not like literary fantasy, there is a real chance that you will hate this. I am very glad that I read it, and also am going to take a significant break from difficult books before I tackle another one. But then I'm probably going to try the Scapegracers series, because Clarke is an author I want to follow. Content notes: Explicit sex, including sadomasochistic sex. Political violence, mostly by authorities. Murdered children, some body horror, and a lot of serious injuries and death. Rating: 8 out of 10

27 December 2024

Wouter Verhelst: Writing an extensible JSON-based DSL with Moose

At work, I've been maintaining a perl script that needs to run a number of steps as part of a release workflow. Initially, that script was very simple, but over time it has grown to do a number of things. And then some of those things did not need to be run all the time. And then we wanted to do this one exceptional thing for this one case. And so on; eventually the script became a big mess of configuration options and unreadable flow, and so I decided that I wanted it to be more configurable. I sat down and spent some time on this, and eventually came up with what I now realize is a domain-specific language (DSL) in JSON, implemented by creating objects in Moose, extensible by writing more object classes. Let me explain how it works. In order to explain, however, I need to explain some perl and Moose basics first. If you already know all that, you can safely skip ahead past the "Preliminaries" section that's next.

Preliminaries

Moose object creation, references. In Moose, creating a class is done something like this:
package Foo;
use v5.40;
use Moose;
has 'attribute' => (
    is  => 'ro',
    isa => 'Str',
    required => 1
);
sub say_something  
    my $self = shift;
    say "Hello there, our attribute is " . $self->attribute;
 
The above is a class that has a single attribute called attribute. To create an object, you use the Moose constructor on the class, and pass it the attributes you want:
use v5.40;
use Foo;
my $foo = Foo->new(attribute => "foo");
$foo->say_something;
(output: Hello there, our attribute is foo) This creates a new object with the attribute attribute set to bar. The attribute accessor is a method generated by Moose, which functions both as a getter and a setter (though in this particular case we made the attribute "ro", meaning read-only, so while it can be set at object creation time it cannot be changed by the setter anymore). So yay, an object. And it has methods, things that we set ourselves. Basic OO, all that. One of the peculiarities of perl is its concept of "lists". Not to be confused with the lists of python -- a concept that is called "arrays" in perl and is somewhat different -- in perl, lists are enumerations of values. They can be used as initializers for arrays or hashes, and they are used as arguments to subroutines. Lists cannot be nested; whenever a hash or array is passed in a list, the list is "flattened", that is, it becomes one big list. This means that the below script is functionally equivalent to the above script that uses our "Foo" object:
use v5.40;
use Foo;
my %args;
$args attribute  = "foo";
my $foo = Foo->new(%args);
$foo->say_something;
(output: Hello there, our attribute is foo) This creates a hash %args wherein we set the attributes that we want to pass to our constructor. We set one attribute in %args, the one called attribute, and then use %args and rely on list flattening to create the object with the same attribute set (list flattening turns a hash into a list of key-value pairs). Perl also has a concept of "references". These are scalar values that point to other values; the other value can be a hash, a list, or another scalar. There is syntax to create a non-scalar value at assignment time, called anonymous references, which is useful when one wants to remember non-scoped values. By default, references are not flattened, and this is what allows you to create multidimensional values in perl; however, it is possible to request list flattening by dereferencing the reference. The below example, again functionally equivalent to the previous two examples, demonstrates this:
use v5.40;
use Foo;
my $args =  ;
$args-> attribute  = "foo";
my $foo = Foo->new(%$args);
$foo->say_something;
(output: Hello there, our attribute is foo) This creates a scalar $args, which is a reference to an anonymous hash. Then, we set the key attribute of that anonymous hash to bar (note the use arrow operator here, which is used to indicate that we want to dereference a reference to a hash), and create the object using that reference, requesting hash dereferencing and flattening by using a double sigil, %$. As a side note, objects in perl are references too, hence the fact that we have to use the dereferencing arrow to access the attributes and methods of Moose objects. Moose attributes don't have to be strings or even simple scalars. They can also be references to hashes or arrays, or even other objects:
package Bar;
use v5.40;
use Moose;
extends 'Foo';
has 'hash_attribute' => (
    is => 'ro',
    isa => 'HashRef[Str]',
    predicate => 'has_hash_attribute',
);
has 'object_attribute' => (
    is => 'ro',
    isa => 'Foo',
    predicate => 'has_object_attribute',
);
sub say_something  
    my $self = shift;
    if($self->has_object_attribute)  
        $self->object_attribute->say_something;
     
    $self->SUPER::say_something unless $self->has_hash_attribute;
    say "We have a hash attribute!"
 
This creates a subclass of Foo called Bar that has a hash attribute called hash_attribute, and an object attribute called object_attribute. Both of them are references; one to a hash, the other to an object. The hash ref is further limited in that it requires that each value in the hash must be a string (this is optional but can occasionally be useful), and the object ref in that it must refer to an object of the class Foo, or any of its subclasses. The predicates used here are extra subroutines that Moose provides if you ask for them, and which allow you to see if an object's attribute has a value or not. The example script would use an object like this:
use v5.40;
use Bar;
my $foo = Foo->new(attribute => "foo");
my $bar = Bar->new(object_attribute => $foo, attribute => "bar");
$bar->say_something;
(output: Hello there, our attribute is foo) This example also shows object inheritance, and methods implemented in child classes. Okay, that's it for perl and Moose basics. On to...

Moose Coercion Moose has a concept of "value coercion". Value coercion allows you to tell Moose that if it sees one thing but expects another, it should convert is using a passed subroutine before assigning the value. That sounds a bit dense without example, so let me show you how it works. Reimaginging the Bar package, we could use coercion to eliminate one object creation step from the creation of a Bar object:
package "Bar";
use v5.40;
use Moose;
use Moose::Util::TypeConstraints;
extends "Foo";
coerce "Foo",
    from "HashRef",
    via   Foo->new(%$_)  ;
has 'hash_attribute' => (
    is => 'ro',
    isa => 'HashRef',
    predicate => 'has_hash_attribute',
);
has 'object_attribute' => (
    is => 'ro',
    isa => 'Foo',
    coerce => 1,
    predicate => 'has_object_attribute',
);
sub say_something  
    my $self = shift;
    if($self->has_object_attribute)  
        $self->object_attribute->say_something;
     
    $self->SUPER::say_something unless $self->has_hash_attribute;
    say "We have a hash attribute!"
 
Okay, let's unpack that a bit. First, we add the Moose::Util::TypeConstraints module to our package. This is required to declare coercions. Then, we declare a coercion to tell Moose how to convert a HashRef to a Foo object: by using the Foo constructor on a flattened list created from the hashref that it is given. Then, we update the definition of the object_attribute to say that it should use coercions. This is not the default, because going through the list of coercions to find the right one has a performance penalty, so if the coercion is not requested then we do not do it. This allows us to simplify declarations. With the updated Bar class, we can simplify our example script to this:
use v5.40;
use Bar;
my $bar = Bar->new(attribute => "bar", object_attribute =>   attribute => "foo"  );
$bar->say_something
(output: Hello there, our attribute is foo) Here, the coercion kicks in because the value object_attribute, which is supposed to be an object of class Foo, is instead a hash ref. Without the coercion, this would produce an error message saying that the type of the object_attribute attribute is not a Foo object. With the coercion, however, the value that we pass to object_attribute is passed to a Foo constructor using list flattening, and then the resulting Foo object is assigned to the object_attribute attribute. Coercion works for more complicated things, too; for instance, you can use coercion to coerce an array of hashes into an array of objects, by creating a subtype first:
package MyCoercions;
use v5.40;
use Moose;
use Moose::Util::TypeConstraints;
use Foo;
subtype "ArrayOfFoo", as "ArrayRef[Foo]";
subtype "ArrayOfHashes", as "ArrayRef[HashRef]";
coerce "ArrayOfFoo", from "ArrayOfHashes", via   [ map   Foo->create(%$_)   @ $_  ]  ;
Ick. That's a bit more complex. What happens here is that we use the map function to iterate over a list of values. The given list of values is @ $_ , which is perl for "dereference the default value as an array reference, and flatten the list of values in that array reference". So the ArrayRef of HashRefs is dereferenced and flattened, and each HashRef in the ArrayRef is passed to the map function. The map function then takes each hash ref in turn and passes it to the block of code that it is also given. In this case, that block is Foo->create(%$_) . In other words, we invoke the create factory method with the flattened hashref as an argument. This returns an object of the correct implementation (assuming our hash ref has a type attribute set), and with all attributes of their object set to the correct value. That value is then returned from the block (this could be made more explicit with a return call, but that is optional, perl defaults a return value to the rvalue of the last expression in a block). The map function then returns a list of all the created objects, which we capture in an anonymous array ref (the [] square brackets), i.e., an ArrayRef of Foo object, passing the Moose requirement of ArrayRef[Foo]. Usually, I tend to put my coercions in a special-purpose package. Although it is not strictly required by Moose, I find that it is useful to do this, because Moose does not allow a coercion to be defined if a coercion for the same type had already been done in a different package. And while it is theoretically possible to make sure you only ever declare a coercion once in your entire codebase, I find that doing so is easier to remember if you put all your coercions in a specific package. Okay, now you understand Moose object coercion! On to...

Dynamic module loading Perl allows loading modules at runtime. In the most simple case, you just use require inside a stringy eval:
my $module = "Foo";
eval "require $module";
This loads "Foo" at runtime. Obviously, the $module string could be a computed value, it does not have to be hardcoded. There are some obvious downsides to doing things this way, mostly in the fact that a computed value can basically be anything and so without proper checks this can quickly become an arbitrary code vulnerability. As such, there are a number of distributions on CPAN to help you with the low-level stuff of figuring out what the possible modules are, and how to load them. For the purposes of my script, I used Module::Pluggable. Its API is fairly simple and straightforward:
package Foo;
use v5.40;
use Moose;
use Module::Pluggable require => 1;
has 'attribute' => (
    is => 'ro',
    isa => 'Str',
);
has 'type' => (
    is => 'ro',
    isa => 'Str',
    required => 1,
);
sub handles_type  
    return 0;
 
sub create  
    my $class = shift;
    my %data = @_;
    foreach my $impl($class->plugins)  
        if($impl->can("handles_type") && $impl->handles_type($data type ))  
            return $impl->new(%data);
         
     
    die "could not find a plugin for type " . $data type ;
 
sub say_something  
    my $self = shift;
    say "Hello there, I am a " . $self->type;
 
The new concept here is the plugins class method, which is added by Module::Pluggable, and which searches perl's library paths for all modules that are in our namespace. The namespace is configurable, but by default it is the name of our module; so in the above example, if there were a package "Foo::Bar" which
  • has a subroutine handles_type
  • that returns a truthy value when passed the value of the type key in a hash that is passed to the create subroutine,
  • then the create subroutine creates a new object with the passed key/value pairs used as attribute initializers.
Let's implement a Foo::Bar package:
package Foo::Bar;
use v5.40;
use Moose;
extends 'Foo';
has 'type' => (
    is => 'ro',
    isa => 'Str',
    required => 1,
);
has 'serves_drinks' => (
    is => 'ro',
    isa => 'Bool',
    default => 0,
);
sub handles_type  
    my $class = shift;
    my $type = shift;
    return $type eq "bar";
 
sub say_something  
    my $self = shift;
    $self->SUPER::say_something;
    say "I serve drinks!" if $self->serves_drinks;
 
We can now indirectly use the Foo::Bar package in our script:
use v5.40;
use Foo;
my $obj = Foo->create(type => bar, serves_drinks => 1);
$obj->say_something;
output:
Hello there, I am a bar.
I serve drinks!
Okay, now you understand all the bits and pieces that are needed to understand how I created the DSL engine. On to...

Putting it all together We're actually quite close already. The create factory method in the last version of our Foo package allows us to decide at run time which module to instantiate an object of, and to load that module at run time. We can use coercion and list flattening to turn a reference to a hash into an object of the correct type. We haven't looked yet at how to turn a JSON data structure into a hash, but that bit is actually ridiculously trivial:
use JSON::MaybeXS;
my $data = decode_json($json_string);
Tada, now $data is a reference to a deserialized version of the JSON string: if the JSON string contained an object, $data is a hashref; if the JSON string contained an array, $data is an arrayref, etc. So, in other words, to create an extensible JSON-based DSL that is implemented by Moose objects, all we need to do is create a system that
  • takes hash refs to set arguments
  • has factory methods to create objects, which
    • uses Module::Pluggable to find the available object classes, and
    • uses the type attribute to figure out which object class to use to create the object
  • uses coercion to convert hash refs into objects using these factory methods
In practice, we could have a JSON file with the following structure:
 
    "description": "do stuff",
    "actions": [
         
            "type": "bar",
            "serves_drinks": true,
         ,
         
            "type": "bar",
            "serves_drinks": false,
         
    ]
 
... and then we could have a Moose object definition like this:
package MyDSL;
use v5.40;
use Moose;
use MyCoercions;
has "description" => (
    is => 'ro',
    isa => 'Str',
);
has 'actions' => (
    is => 'ro',
    isa => 'ArrayOfFoo'
    coerce => 1,
    required => 1,
);
sub say_something  
    say "Hello there, I am described as " . $self->description . " and I am performing my actions: ";
    foreach my $action(@ $self->actions )  
        $action->say_something;
     
 
Now, we can write a script that loads this JSON file and create a new object using the flattened arguments:
use v5.40;
use MyDSL;
use JSON::MaybeXS;
my $input_file_name = shift;
my $args = do  
    local $/ = undef;
    open my $input_fh, "<", $input_file_name or die "could not open file";
    <$input_fh>;
 ;
$args = decode_json($args);
my $dsl = MyDSL->new(%$args);
$dsl->say_something
Output:
Hello there, I am described as do stuff and I am performing my actions:
Hello there, I am a bar
I am serving drinks!
Hello there, I am a bar
In some more detail, this will:
  • Read the JSON file and deserialize it;
  • Pass the object keys in the JSON file as arguments to a constructor of the MyDSL class;
  • The MyDSL class then uses those arguments to set its attributes, using Moose coercion to convert the "actions" array of hashes into an array of Foo::Bar objects.
  • Perform the say_something method on the MyDSL object
Once this is written, extending the scheme to also support a "quux" type simply requires writing a Foo::Quux class, making sure it has a method handles_type that returns a truthy value when called with quux as the argument, and installing it into the perl library path. This is rather easy to do. It can even be extended deeper, too; if the quux type requires a list of arguments rather than just a single argument, it could itself also have an array attribute with relevant coercions. These coercions could then be used to convert the list of arguments into an array of objects of the correct type, using the same schema as above. The actual DSL is of course somewhat more complex, and also actually does something useful, in contrast to the DSL that we define here which just says things. Creating an object that actually performs some action when required is left as an exercise to the reader.

24 December 2024

Russ Allbery: Review: Number Go Up

Review: Number Go Up, by Zeke Faux
Publisher: Crown Currency
Copyright: 2023
Printing: 2024
ISBN: 0-593-44382-9
Format: Kindle
Pages: 373
Number Go Up is a cross between a history and a first-person account of investigative journalism around the cryptocurrency bubble and subsequent collapse in 2022. The edition I read has an afterward from June 2024 that brings the story up to date with Sam Bankman-Fried's trial and a few other events. Zeke Faux is a reporter for Bloomberg News and a fellow of New America. Last year, I read Michael Lewis's Going Infinite, a somewhat-sympathetic book-length profile of Sam Bankman-Fried that made a lot of people angry. One of the common refrains at the time was that people should read Number Go Up instead, and since I'm happy to read more about the absurdities of the cryptocurrency world, I finally got around to reading the other big crypto book of 2023. This is a good book, with some caveats that I am about to explain at absurd length. If you want a skeptical history of the cryptocurrency bubble, you should read it. People who think that it's somehow in competition with Michael Lewis's book or who think the two books disagree (including Faux himself) have profoundly missed the point of Going Infinite. I agree with Matt Levine: Both of these books are worth your time if this is the sort of thing you like reading about. But (much) more on Faux's disagreements with Lewis later. The frame of Number Go Up is Faux's quixotic quest to prove that Tether is a fraud. To review this book, I therefore need to briefly explain what Tether is. This is only the first of many extended digressions. One natural way to buy cryptocurrency would be to follow the same pattern as a stock brokerage account. You would deposit some amount of money into the account (or connect the brokerage account to your bank account), and then exchange money for cryptocurrency or vice versa, using bank transfers to put money in or take it out. However, there are several problems with this. One is that swapping cryptocurrency for money is awkward and sometimes expensive. Another is that holding people's investment money for them is usually highly regulated, partly for customer safety but also to prevent money laundering. These are often called KYC laws (Know Your Customer), and the regulation-hostile world of cryptocurrency didn't want to comply with them. Tether is a stablecoin, which means that the company behind Tether attempts to guarantee that one Tether is always worth exactly one US dollar. It is not a speculative investment like Bitcoin; it's a cryptocurrency substitute for dollars. People exchange dollars for Tether to get their money into the system and then settle all of their subsequent trades in Tether, only converting the Tether back to dollars when they want to take their money out of cryptocurrency entirely. In essence, Tether functions like the cash reserve in a brokerage account: Your Tether holdings are supposedly guaranteed to be equivalent to US dollars, you can withdraw them at any time, and because you can do so, you don't bother, instead leaving your money in the reserve account while you contemplate what new coin you want to buy. As with a bank, this system rests on the assurance that one can always exchange one Tether for one US dollar. The instant people stop believing this is true, people will scramble to get their money out of Tether, creating the equivalent of a bank run. Since Tether is not a regulated bank or broker and has no deposit insurance or strong legal protections, the primary defense against a run on Tether is Tether's promise that they hold enough liquid assets to be able to hand out dollars to everyone who wants to redeem Tether. (A secondary defense that I wish Faux had mentioned is that Tether limits redemptions to registered accounts redeeming more than $100,000, which is a tiny fraction of the people who hold Tether, but for most purposes this doesn't matter because that promise is sufficient to maintain the peg with the dollar.) Faux's firmly-held belief throughout this book is that Tether is lying. He believes they do not have enough money to redeem all existing Tether coins, and that rather than backing every coin with very safe liquid assets, they are using the dollars deposited in the system to make illiquid and risky investments. Faux never finds the evidence that he's looking for, which makes this narrative choice feel strange. His theory was tested when there was a run on Tether following the collapse of the Terra stablecoin. Tether passed without apparent difficulty, redeeming $16B or about 20% of the outstanding Tether coins. This doesn't mean Faux is wrong; being able to redeem 20% of the outstanding tokens is very different from being able to redeem 100%, and Tether has been fined for lying about its reserves. But Tether is clearly more stable than Faux thought it was, which makes the main narrative of the book weirdly unsatisfying. If he admitted he might be wrong, I would give him credit for showing his work even if it didn't lead where he expected, but instead he pivots to focusing on Tether's role in money laundering without acknowledging that his original theory took a serious blow. In Faux's pursuit of Tether, he wanders through most of the other elements of the cryptocurrency bubble, and that's the strength of this book. Rather than write Number Go Up as a traditional history, Faux chooses to closely follow his own thought processes and curiosity. This has the advantage of giving Faux an easy and natural narrative, something that non-fiction books of this type can struggle with, and it lets Faux show how confusing and off-putting the cryptocurrency world is to an outsider. The best parts of this book were the parts unrelated to Tether. Faux provides an excellent summary of the Axie Infinity speculative bubble and even traveled to the Philippines to interview people who were directly affected. He then wandered through the bizarre world of NFTs, and his first-hand account of purchasing one (specifically a Mutant Ape) to get entrance to a party (which sounded like a miserable experience I would pay money to get out of) really drives home how sketchy and weird cryptocurrency-related software and markets can be. He also went to El Salvador to talk to people directly about the country's supposed embrace of Bitcoin, and there's no substitute for that type of reporting to show how exaggerated and dishonest the claims of cryptocurrency adoption are. The disadvantage of this personal focus on Faux himself is that it sometimes feels tedious or sensationalized. I was much less interested in his unsuccessful attempts to interview the founder of Tether than Faux was, and while the digression into forced labor compounds in Cambodia devoted to pig butchering scams was informative (and horrific), I think Faux leaned too heavily on an indirect link to Tether. His argument is that cryptocurrency enables a type of money laundering that is particularly well-suited to supporting scams, but both scams and this type of economic slavery existed before cryptocurrency and will exist afterwards. He did not make a very strong case that Tether was uniquely valuable as a money laundering service, as opposed to a currently useful tool that would be replaced with some other tool should it go away. This part of the book is essentially an argument that money laundering is bad because it enables crime, and sure, to an extent I agree. But if you're going to put this much emphasis on the evils of money laundering, I think you need to at least acknowledge that many people outside the United States do not want to give US government, which is often openly hostile to them, veto power over their financial transactions. Faux does not. The other big complaint I have with this book, and with a lot of other reporting on cryptocurrency, is that Faux is sloppy with the term "Ponzi scheme." This is going to sound like nit-picking, but I think this sloppiness matters because it may obscure an ongoing a shift in cryptocurrency markets. A Ponzi scheme is not any speculative bubble. It is a very specific type of fraud in which investors are promised improbably high returns at very low risk and with safe principal. These returns are paid out, not via investment in some underlying enterprise, but by taking the money from new investments and paying it to earlier investors. Ponzi schemes are doomed because satisfying their promises requires a constantly increasing flow of new investors. Since the population of the world is finite, all Ponzi schemes are mathematically guaranteed to eventually fail, often in a sudden death spiral of ever-increasing promises to lure new investors when the investment stream starts to dry up. There are some Ponzi schemes in cryptocurrency, but most practices that are called Ponzi schemes are not. For example, Faux calls Axie Infinity a Ponzi scheme, but it was missing the critical elements of promised safe returns and fraudulently paying returns from the investments of later investors. It was simply a speculative bubble that people bought into on the assumption that its price would increase, and like any speculative bubble those who sold before the peak made money at the expense of those who bought at the peak. The reason why this matters is that Ponzi schemes are a self-correcting problem. One can decry the damage caused when they collapse, but one can also feel the reassuring certainty that they will inevitably collapse and prove the skeptics correct. The same is not true of speculative assets in general. You may think that the lack of an underlying economic justification for prices means that a speculative bubble is guaranteed to collapse eventually, but in the famous words of Gary Schilling, "markets can remain irrational a lot longer than you and I can remain solvent." One of the people Faux interviews explains this distinction to him directly:
Rong explained that in a true Ponzi scheme, the organizer would have to handle the "fraud money." Instead, he gave the sneakers away and then only took a small cut of each trade. "The users are trading between each other. They are not going through me, right?" Rong said. Essentially, he was arguing that by downloading the Stepn app and walking to earn tokens, crypto bros were Ponzi'ing themselves.
Faux is openly contemptuous of this response, but it is technically correct. Stepn is not a Ponzi scheme; it's a speculative bubble. There are no guaranteed returns being paid out of later investments and no promise that your principal is safe. People are buying in at price that you may consider irrational, but Stepn never promised you would get your money back, let alone make a profit, and therefore it doesn't have the exponential progression of a Ponzi scheme. One can argue that this is a distinction without a moral difference, and personally I would agree, but it matters immensely if one is trying to analyze the future of cryptocurrencies. Schemes as transparently unstable as Stepn (which gives you coins for exercise and then tries to claim those coins have value through some vigorous hand-waving) are nearly as certain as Ponzi schemes to eventually collapse. But it's also possible to create a stable business around allowing large numbers of people to regularly lose money to small numbers of sophisticated players who are collecting all of the winnings. It's called a poker room at a casino, and no one thinks poker rooms are Ponzi schemes or are doomed to collapse, even though nearly everyone who plays poker will lose money. This is the part of the story that I think Faux largely missed, and which Michael Lewis highlights in Going Infinite. FTX was a legitimate business that made money (a lot of money) off of trading fees, in much the same way that a casino makes money off of poker rooms. Lots of people want to bet on cryptocurrencies, similar to how lots of people want to play poker. Some of those people will win; most of those people will lose. The casino doesn't care. Its profit comes from taking a little bit of each pot, regardless of who wins. Bankman-Fried also speculated with customer funds, and therefore FTX collapsed, but there is no inherent reason why the core exchange business cannot be stable if people continue to want to speculate in cryptocurrencies. Perhaps people will get tired of this method of gambling, but poker has been going strong for 200 years. It's also important to note that although trading fees are the most obvious way to be a profitable cryptocurrency casino, they're not the only way. Wall Street firms specialize in finding creative ways to take a cut of every financial transaction, and many of those methods are more sophisticated than fees. They are so good at this that buying and selling stock through trading apps like Robinhood is free. The money to run the brokerage platform comes from companies that are delighted to pay for the opportunity to handle stock trades by day traders with a phone app. This is not, as some conspiracy theories would have you believe, due to some sort of fraudulent price manipulation. It is because the average person with a Robinhood phone app is sufficiently unsophisticated that companies that have invested in complex financial modeling will make a steady profit taking the other side of their trades, mostly because of the spread (the difference between offered buy and sell prices). Faux is so caught up in looking for Ponzi schemes and fraud that I think he misses this aspect of cryptocurrency's transformation. Wall Street trading firms aren't piling into cryptocurrency because they want to do securities fraud. They're entering this market because there seems to be persistent demand for this form of gambling, cryptocurrency markets reward complex financial engineering, and running a legal casino is a profitable business model. Michael Lewis appears as a character in this book, and Faux portrays him quite negatively. The root of this animosity appears to stem from a cryptocurrency conference in the Bahamas that Faux attended. Lewis interviewed Bankman-Fried on stage, and, from Faux's account, his questions were fawning and he praised cryptocurrencies in ways that Faux is certain he knew were untrue. From that point on, Faux treats Lewis as an apologist for the cryptocurrency industry and for Sam Bankman-Fried specifically. I think this is a legitimate criticism of Lewis's methods of getting close to the people he wants to write about, but I think Faux also makes the common mistake of assuming Lewis is a muckraking reporter like himself. This has never been what Lewis is interested in. He writes about people he finds interesting and that he thinks a reader will also find interesting. One can legitimately accuse him of being credulous, but that's partly because he's not even trying to do the same thing Faux is doing. He's not trying to judge; he's trying to understand. This shows when it comes to the parts of this book about Sam Bankman-Fried. Faux's default assumption is that everyone involved in cryptocurrency is knowingly doing fraud, and a lot of his research is looking for evidence to support the conclusion he had already reached. I don't think there's anything inherently wrong with that approach: Faux is largely, although not entirely, correct, and this type of hostile journalism is incredibly valuable for society at large. Upton Sinclair didn't start writing The Jungle with an open mind about the meat-packing industry. But where Faux and Lewis disagree on Bankman-Fried's motivations and intentions, I think Lewis has the much stronger argument. Faux's position is that Bankman-Fried always intended to steal people's money through fraud, perhaps to fund his effective altruism donations, and his protestations that he made mistakes and misplaced funds are obvious lies. This is an appealing narrative if one is looking for a simple villain, but Faux's evidence in support of this is weak. He mostly argues through stereotype: Bankman-Fried was a physics major and a Jane Street trader and therefore could not possibly be the type of person to misplace large amounts of money or miscalculate risk. If he wants to understand how that could be possible, he could read Going Infinite? I find it completely credible that someone with what appears to be uncontrolled, severe ADHD could be adept at trading and calculating probabilities and yet also misplace millions of dollars of assets because he wasn't thinking about them and therefore they stopped existing. Lewis made a lot of people angry by being somewhat sympathetic to someone few people wanted to be sympathetic towards, but Faux (and many others) are also misrepresenting his position. Lewis agrees that Bankman-Fried intentionally intermingled customer funds with his hedge fund and agrees that he lied about doing this. His only contention is that Bankman-Fried didn't do this to steal the money; instead, he invested customer money in risky bets that he thought would pay off. In support of this, Lewis made a prediction that was widely scoffed at, namely that much less of FTX's money was missing than was claimed, and that likely most or all of it would be found. And, well, Lewis was basically correct? The FTX bankruptcy is now expected to recover considerably more than the amount of money owed to creditors. Faux argues that this is only because the bankruptcy clawed back assets and cryptocurrencies have gone up considerably since the FTX bankruptcy, and therefore that the lost money was just replaced by unexpected windfall profits on other investments, but I don't think this point is as strong as he thinks it is. Bankman-Fried lost money on some of what he did with customer funds, made money on other things, and if he'd been able to freeze withdrawals for the year that the bankruptcy froze them, it does appear most of the money would have been recoverable. This does not make what he did legal or morally right, but no one is arguing that, only that he didn't intentionally steal money for his own personal gain or for effective altruism donations. And on that point, I don't think Faux is giving Lewis's argument enough credit. I have a lot of complaints about this book because I know way too much about this topic than anyone should probably know. I think Faux missed the plot in a couple of places, and I wish someone would write a book about where cryptocurrency markets are currently going. (Matt Levine's Money Stuff newsletter is quite good, but it's about all sorts of things other than cryptocurrency and isn't designed to tell a coherent story.) But if you know less about cryptocurrency and just want to hear the details of the run-up to the 2022 bubble, this is a great book for that. Faux is writing for people who are already skeptical and is not going to convince people who are cryptocurrency true believers, but that's fine. The details are largely correct (and extensively footnoted) and will satisfy most people's curiosity. Lewis's Going Infinite is a better book, though. It's not the same type of book at all, and it will not give you the broader overview of the cryptocurrency world. But if you're curious about what was going through the head of someone at the center of all of this chaos, I think Lewis's analysis is much stronger than Faux's. I'm happy I read both books. Rating: 8 out of 10

23 December 2024

Sahil Dhiman: Debian Mirrors Hierarchy

After finding AlmaLinux mirror sync capacity at Tier 0 (or Tier 1, however you look at it) is around 140 Gbps, I wanted to find source and hierarchy in Debian mirroring systems. There are two main types of mirrors in Debian - Debian package mirrors (for package installs and updates) and Debian CD mirrors (for ISO and others medias). Let s talk about package mirrors (and it s hierarchy) first.

Package mirror hierarchy Trace file was a good starting point for checking upstream for a package mirror in Debian. It resides at <URL>/debian/project/trace/_traces and shows flow of data. Sample trace file from jing.rocks s mirror. It showed, canonical source for packages is ftp-master.debian.org. Checking via https://db.debian.org/machines.cgi, showed it s fasolo.d.o hosted at Brown University, US. This serves as Master Archive Server , making it a Tier 0 mirror. It s entry mentions that it has 1 Gbps shared LAN connectivity (dated information?) but it only has to push to 3 other machines/sites. Side note - .d.o is .debian.org As shown on https://mirror-master.debian.org/status/mirror-hierarchy.html, the three sites are:
  • syncproxy2.eu.debian.org ie smit.d.o hosted by University of Twente, Netherlands with 2x10 Gbps connectivity.
  • syncproxy4.eu.debian.org ie schmelzer.d.o hosted by Conova in Austria with 2x10 Gbps connectivity.
  • syncproxy2.wna.debian.org - https://db.debian.org/machines.cgi entry mentions it being hosted at UBC here, but IP seems to be pointing to OSUOSL IP range as of now. IIRC few months ago, syncproxy2.wna.d.o was made to point to other host due to some issue (?). mirror-osuosl.d.o seems to be serving as syncproxy2.wna.d.o now. Bandwidth isn t explicitly mentioned but from my experience seeing bandwidths which other free software projects hosted at OSUOSL have, it would be atleast 10 Gbps and maybe more for Debian.

                     syncproxy2.eu.d.o (NL) ---> to the world
                    /
ftp-master.d.o (US) -- syncproxy4.eu.d.o (AT)  --> to the world 
                    \
                     syncproxy2.wna.d.o (US) --> to the world
A visualation of flow of package from ftp-master.d.o
These form the Debian Tier 1 mirror network, as all the mirrors sync from them. So Debian has atleast 50 Gbps+ capacity at Tier 1. A normal Debian user might never directly interact with any of these 3 machines, but every Debian package they run/download/install flows through these machines. Though, I m unsure what wna stands for in syncproxy2.wna.d.o. NA probably is North America and W is west (coast)? If you know, do let me know. After Tier 1, there are a few more syncproxies (detailed below). There are atleast 45 mirrors at Tier 2, updates for which are directly pushed from the three Tier 1 sync proxies. Most country mirrors i.e. ftp..debian.org are at Tier 2 too (barring a few like ftp.au.d.o, ftp.nz.do etc). Coming back to Sync proxies at Tier 2:
  • syncproxy3.wna.debian.org - gretchaninov.d.o which is marked as syncproxy2 on db.d.o (information dated). It s hosted in University of British Columbia, Canada, where a lot of Debian infrastructure including Salsa is hosted.
  • syncproxy.eu.debian.org - Croatian Academic and Research Network managed machine. CNAME directs to debian.carnet.hr.
  • syncproxy.au.debian.org - mirror-anu.d.o hosted by Australian National University with 100Mbps connectivity. Closest sync proxy for all Australian mirrors.
  • syncproxy4.wna.debian.org - syncproxy-aws-wna-01.d.o hosted in AWS, in US (according to GeoIP). IPv6 only (CNAME to syncproxy-aws-wna-01.debian.org. which only has an AAAA record, no A record). A m6g.2xlarge instance which has speeds upto 10 Gbps.
Coming back to https://mirror-master.debian.org/status/mirror-hierarchy.html, one can see chain extend till Tier 6 like in case of this mirror in AU which should add some latency for the updates from being pushed at ftp-master.d.o to them. Ideally, which shouldn t be a problem as https://www.debian.org/mirror/ftpmirror#when mentions The main archive gets updated four times a day . In my case, I get my updates from NITC mirror, so my updates flows from US > US > TW > IN > me in IN. CDNs have to internally manage cache purging too unlike normal mirrors which directly serve static file. Both deb.debian.org (sponsored by Fastly) and cdn-aws.deb.debian.org (sponsored by Amazon Cloudfront) sync from following CDN backends: See deb.d.o trace file and cdn-aws.deb.d.o trace file. (Thanks to Philipp Kern for the heads up here.)

CD image mirrors Hierarchy Till now, I have only talked about Debian package mirrors. When you see /debian directory on various mirrors, they re usually for package install and updates. If you want to grab the latest (and greatest) Debian ISO, you go to Debian CD (as they re still called) mirror site. casulana.d.o is mentioned as CD builder site hosted by Bytemark while pettersson-ng.d.o is mentioned as CD publishing server hosted at Academic Computer Club in Ume , Sweden. Primary download site for Debian CD when you click download on debian.org homepage is https://cdimage.debian.org/debian-cd/ is hosted here as well. This essentially becomes Tier 0 mirror for Debian CD. All Debian CD mirrors are downstream to it.
pettersson-ng.d.o / cdimage.d.o (SE) ---> to the world
A visualation of flow of Debian CD from cdimage.d.o
Academic Computer Club s mirror setup uses a combination of multiple machines (called frontends and offloading servers) to load balance requests. Their document setup is a highly recommended read. Also, in that document, they mention , All machines are reachable via both IPv4 and IPv6 and connected with 10 or 25 gigabit Ethernet, external bandwidth available is 200 gigabit/s. For completeness sake, following mirror (or mirror systems) exists too for Debian: Debian heavily rely on various organizations to donate resources (hosting and hardware) to distribute and update Debian. Compiling above information made me thankful to all these organizations. Many thanks to DSA and mirror team as well for managing these stuffs. I relied heavily on https://db.debian.org/machines.cgi which seems to be manually updated, so things might have changed along the way. If anything looks amiss, feel free to ping.

Simon Josefsson: OpenSSH and Git on a Post-Quantum SPHINCS+

Are you aware that Git commits and tags may be signed using OpenSSH? Git signatures may be used to improve integrity and authentication of our software supply-chain. Popular signature algorithms include Ed25519, ECDSA and RSA. Did you consider that these algorithms may not be safe if someone builds a post-quantum computer? As you may recall, I have earlier blogged about the efficient post-quantum key agreement mechanism called Streamlined NTRU Prime and its use in SSH and I have attempted to promote the conservatively designed Classic McEliece in a similar way, although it remains to be adopted. What post-quantum signature algorithms are available? There is an effort by NIST to standardize post-quantum algorithms, and they have a category for signature algorithms. According to wikipedia, after round three the selected algorithms are CRYSTALS-Dilithium, FALCON and SPHINCS+. Of these, SPHINCS+ appears to be a conservative choice suitable for long-term digital signatures. Can we get this to work? Recall that Git uses the ssh-keygen tool from OpenSSH to perform signing and verification. To refresh your memory, let s study the commands that Git uses under the hood for Ed25519. First generate a Ed25519 private key:
jas@kaka:~$ ssh-keygen -t ed25519 -f my_ed25519_key -P ""
Generating public/private ed25519 key pair.
Your identification has been saved in my_ed25519_key
Your public key has been saved in my_ed25519_key.pub
The key fingerprint is:
SHA256:fDa5+jmC2+/aiLhWeWA3IV8Wj6yMNTSuRzqUZlIGlXQ jas@kaka
The key's randomart image is:
+--[ED25519 256]--+
     .+=.E ..      
      oo=.ooo      
     . =o=+o .     
      =oO+o .      
      .=+S.=       
       oo.o o      
      . o  .       
     ...o.+..      
    .o.o.=**.      
+----[SHA256]-----+
jas@kaka:~$ cat my_ed25519_key
-----BEGIN OPENSSH PRIVATE KEY-----
b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAMwAAAAtzc2gtZW
QyNTUxOQAAACAWP/aZ8hzN0WNRMSpjzbgW1tJXNd2v6/dnbKaQt7iIBQAAAJCeDotOng6L
TgAAAAtzc2gtZWQyNTUxOQAAACAWP/aZ8hzN0WNRMSpjzbgW1tJXNd2v6/dnbKaQt7iIBQ
AAAEBFRvzgcD3YItl9AMmVK4xDKj8NTg4h2Sluj0/x7aSPlhY/9pnyHM3RY1ExKmPNuBbW
0lc13a/r92dsppC3uIgFAAAACGphc0BrYWthAQIDBAU=
-----END OPENSSH PRIVATE KEY-----
jas@kaka:~$ cat my_ed25519_key.pub 
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIBY/9pnyHM3RY1ExKmPNuBbW0lc13a/r92dsppC3uIgF jas@kaka
jas@kaka:~$ 
Then let s sign something with this key:
jas@kaka:~$ echo "Hello world!" > msg
jas@kaka:~$ ssh-keygen -Y sign -f my_ed25519_key -n my-namespace msg
Signing file msg
Write signature to msg.sig
jas@kaka:~$ cat msg.sig 
-----BEGIN SSH SIGNATURE-----
U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgFj/2mfIczdFjUTEqY824FtbSVz
Xdr+v3Z2ymkLe4iAUAAAAMbXktbmFtZXNwYWNlAAAAAAAAAAZzaGE1MTIAAABTAAAAC3Nz
aC1lZDI1NTE5AAAAQLmWsq05tqOOZIJqjxy5ZP/YRFoaX30lfIllmfyoeM5lpVnxJ3ZxU8
SF0KodDr8Rtukg2N3Xo80NGvZOzbG/9Aw=
-----END SSH SIGNATURE-----
jas@kaka:~$
Now let s create a list of trusted public-keys and associated identities:
jas@kaka:~$ echo 'my.name@example.org ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIBY/9pnyHM3RY1ExKmPNuBbW0lc13a/r92dsppC3uIgF' > allowed-signers
jas@kaka:~$ 
Then let s verify the message we just signed:
jas@kaka:~$ cat msg   ssh-keygen -Y verify -f allowed-signers -I my.name@example.org -n my-namespace -s msg.sig
Good "my-namespace" signature for my.name@example.org with ED25519 key SHA256:fDa5+jmC2+/aiLhWeWA3IV8Wj6yMNTSuRzqUZlIGlXQ
jas@kaka:~$ 
I have implemented support for SPHINCS+ in OpenSSH. This is early work, but I wanted to announce it to get discussion of some of the details going and to make people aware of it. What would a better way to demonstrate SPHINCS+ support in OpenSSH than by validating the Git commit that implements it using itself? Here is how to proceed, first get a suitable development environment up and running. I m using a Debian container launched in a protected environment using podman.
jas@kaka:~$ podman run -it --rm debian:stable
Then install the necessary build dependencies for OpenSSH.
# apt-get update 
# apt-get install git build-essential autoconf libz-dev libssl-dev
Now clone my OpenSSH branch with the SPHINCS+ implentation and build it. You may browse the commit on GitHub first if you are curious.
# cd
# git clone https://github.com/jas4711/openssh-portable.git -b sphincsp
# cd openssh-portable
# autoreconf -fvi
# ./configure
# make
Configure a Git allowed signers list with my SPHINCS+ public key (make sure to keep the public key on one line with the whitespace being one ASCII SPC character):
# mkdir -pv ~/.ssh
# echo 'simon@josefsson.org ssh-sphincsplus@openssh.com AAAAG3NzaC1zcGhpbmNzcGx1c0BvcGVuc3NoLmNvbQAAAECI6eacTxjB36xcPtP0ZyxJNIGCN350GluLD5h0KjKDsZLNmNaPSFH2ynWyKZKOF5eRPIMMKSCIV75y+KP9d6w3' > ~/.ssh/allowed_signers
# git config gpg.ssh.allowedSignersFile ~/.ssh/allowed_signers
Then verify the commit using the newly built ssh-keygen binary:
# PATH=$PWD:$PATH
# git log -1 --show-signature
commit ce0b590071e2dc845373734655192241a4ace94b (HEAD -> sphincsp, origin/sphincsp)
Good "git" signature for simon@josefsson.org with SPHINCSPLUS key SHA256:rkAa0fX0lQf/7V7QmuJHSI44L/PAPPsdWpis4nML7EQ
Author: Simon Josefsson <simon@josefsson.org>
Date:   Tue Dec 3 18:44:25 2024 +0100
    Add SPHINCS+.
# git verify-commit ce0b590071e2dc845373734655192241a4ace94b
Good "git" signature for simon@josefsson.org with SPHINCSPLUS key SHA256:rkAa0fX0lQf/7V7QmuJHSI44L/PAPPsdWpis4nML7EQ
# 
Yay! So what are some considerations? SPHINCS+ comes in many different variants. First it comes with three security levels approximately matching 128/192/256 bit symmetric key strengths. Second choice is between the SHA2-256, SHAKE256 (SHA-3) and Haraka hash algorithms. Final choice is between a robust and a simple variant with different security and performance characteristics. To get going, I picked the sphincss256sha256robust SPHINCS+ implementation from SUPERCOP 20241022. There is a good size comparison table in the sphincsplus implementation, if you want to consider alternative variants. SPHINCS+ public-keys are really small, as you can see in the allowed signers file. This is really good because they are handled by humans and often by cut n paste. What about private keys? They are slightly longer than Ed25519 private keys but shorter than typical RSA private keys.
# ssh-keygen -t sphincsplus -f my_sphincsplus_key -P ""
Generating public/private sphincsplus key pair.
Your identification has been saved in my_sphincsplus_key
Your public key has been saved in my_sphincsplus_key.pub
The key fingerprint is:
SHA256:4rNfXdmLo/ySQiWYzsBhZIvgLu9sQQz7upG8clKziBg root@ad600ff56253
The key's randomart image is:
+[SPHINCSPLUS 256-+
  .  .o            
 o . oo.           
  = .o.. o         
 o o  o o . .   o  
 .+    = S o   o . 
 Eo=  . + . . .. . 
 =*.+  o . . oo .  
 B+=    o o.o. .   
 o*o   ... .oo.    
+----[SHA256]-----+
# cat my_sphincsplus_key.pub 
ssh-sphincsplus@openssh.com AAAAG3NzaC1zcGhpbmNzcGx1c0BvcGVuc3NoLmNvbQAAAEAltAX1VhZ8pdW9FgC+NdM6QfLxVXVaf1v2yW4v+tk2Oj5lxmVgZftfT37GOMOlK9iBm9SQHZZVYZddkEJ9F1D7 root@ad600ff56253
# cat my_sphincsplus_key 
-----BEGIN OPENSSH PRIVATE KEY-----
b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAYwAAABtzc2gtc3
BoaW5jc3BsdXNAb3BlbnNzaC5jb20AAABAJbQF9VYWfKXVvRYAvjXTOkHy8VV1Wn9b9slu
L/rZNjo+ZcZlYGX7X09+xjjDpSvYgZvUkB2WVWGXXZBCfRdQ+wAAAQidiIwanYiMGgAAAB
tzc2gtc3BoaW5jc3BsdXNAb3BlbnNzaC5jb20AAABAJbQF9VYWfKXVvRYAvjXTOkHy8VV1
Wn9b9sluL/rZNjo+ZcZlYGX7X09+xjjDpSvYgZvUkB2WVWGXXZBCfRdQ+wAAAIAbwBxEhA
NYzITN6VeCMqUyvw/59JM+WOLXBlRbu3R8qS7ljc4qFVWUtmhy8B3t9e4jrhdO6w0n5I4l
mnLnBi2hJbQF9VYWfKXVvRYAvjXTOkHy8VV1Wn9b9sluL/rZNjo+ZcZlYGX7X09+xjjDpS
vYgZvUkB2WVWGXXZBCfRdQ+wAAABFyb290QGFkNjAwZmY1NjI1MwECAwQ=
-----END OPENSSH PRIVATE KEY-----
# 
Signature size? Now here is the challenge, for this variant the size is around 29kb or close to 600 lines of base64 data:
# git cat-file -p ce0b590071e2dc845373734655192241a4ace94b   head -10
tree ede42093e7d5acd37fde02065a4a19ac1f418703
parent 826483d51a9fee60703298bbf839d9ce37943474
author Simon Josefsson <simon@josefsson.org> 1733247865 +0100
committer Simon Josefsson <simon@josefsson.org> 1734907869 +0100
gpgsig -----BEGIN SSH SIGNATURE-----
 U1NIU0lHAAAAAQAAAGMAAAAbc3NoLXNwaGluY3NwbHVzQG9wZW5zc2guY29tAAAAQIjp5p
 xPGMHfrFw+0/RnLEk0gYI3fnQaW4sPmHQqMoOxks2Y1o9IUfbKdbIpko4Xl5E8gwwpIIhX
 vnL4o/13rDcAAAADZ2l0AAAAAAAAAAZzaGE1MTIAAHSDAAAAG3NzaC1zcGhpbmNzcGx1c0
 BvcGVuc3NoLmNvbQAAdGDHlobgfgkKKQBo3UHmnEnNXczCMNdzJmeYJau67QM6xZcAU+d+
 2mvhbksm5D34m75DWEngzBb3usJTqWJeeDdplHHRe3BKVCQ05LHqRYzcSdN6eoeZqoOBvR
# git cat-file -p ce0b590071e2dc845373734655192241a4ace94b   tail -5 
 ChvXUk4jfiNp85RDZ1kljVecfdB2/6CHFRtxrKHJRDiIavYjucgHF1bjz0fqaOSGa90UYL
 RZjZ0OhdHOQjNP5QErlIOcZeqcnwi0+RtCJ1D1wH2psuXIQEyr1mCA==
 -----END SSH SIGNATURE-----
Add SPHINCS+.
# git cat-file -p ce0b590071e2dc845373734655192241a4ace94b   wc -l
579
# 
What about performance? Verification is really fast:
# time git verify-commit ce0b590071e2dc845373734655192241a4ace94b
Good "git" signature for simon@josefsson.org with SPHINCSPLUS key SHA256:rkAa0fX0lQf/7V7QmuJHSI44L/PAPPsdWpis4nML7EQ
real	0m0.010s
user	0m0.005s
sys	0m0.005s
# 
On this machine, verifying an Ed25519 signature is a couple of times slower, and needs around 0.07 seconds. Signing is slower, it takes a bit over 2 seconds on my laptop.
# echo "Hello world!" > msg
# time ssh-keygen -Y sign -f my_sphincsplus_key -n my-namespace msg
Signing file msg
Write signature to msg.sig
real	0m2.226s
user	0m2.226s
sys	0m0.000s
# echo 'my.name@example.org ssh-sphincsplus@openssh.com AAAAG3NzaC1zcGhpbmNzcGx1c0BvcGVuc3NoLmNvbQAAAEAltAX1VhZ8pdW9FgC+NdM6QfLxVXVaf1v2yW4v+tk2Oj5lxmVgZftfT37GOMOlK9iBm9SQHZZVYZddkEJ9F1D7' > allowed-signers
# cat msg   ssh-keygen -Y verify -f allowed-signers -I my.name@example.org -n my-namespace -s msg.sig
Good "my-namespace" signature for my.name@example.org with SPHINCSPLUS key SHA256:4rNfXdmLo/ySQiWYzsBhZIvgLu9sQQz7upG8clKziBg
# 
Welcome to our new world of Post-Quantum safe digital signatures of Git commits, and Happy Hacking!

21 December 2024

Dirk Eddelbuettel: anytime 0.3.11 on CRAN: Maintenance

A follow-up release 0.3.11 to the recent 0.3.10 release release of the anytime package arrived on CRAN two days ago. The package is fairly feature-complete, and code and functionality remain mature and stable, of course. anytime is a very focused package aiming to do just one thing really well: to convert anything in integer, numeric, character, factor, ordered, input format to either POSIXct (when called as anytime) or Date objects (when called as anydate) and to do so without requiring a format string as well as accomodating different formats in one input vector. See the anytime page, or the GitHub repo for a few examples, and the beautiful documentation site for all documentation. This release simply skips one test file. CRAN labeled an error M1mac yet it did not reproduce on any of the other M1 macOS I can access (macbuilder, GitHub Actions) as this appeared related to a local setting of timezone values I could not reproduce anywwhere. So the only way to get rid of the fail is to not to run the test. Needless to say the upload process was a little tedious as I got the passive-aggressive not responding treatment on a first upload and the required email answer it lead to. Anyway, after a few days, and even more deep breaths, it is taken care of and now the package result standing is (at least currently) pristinely clean. The short list of changes follows.

Changes in anytime version 0.3.11 (2024-12-18)
  • Skip a test file

Courtesy of my CRANberries, there is also a diffstat report of changes relative to the previous release. The issue tracker tracker off the GitHub repo can be use for questions and comments. More information about the package is at the package page, the GitHub repo and the documentation site.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can now sponsor me at GitHub.

20 December 2024

Noah Meyerhans: Local Development VM Management

A coworker asked recently about how people use VMs locally for dev work, so I figured I d take a few minutes to write up a bit about what I do. There are many use cases for local virtual machines in software development and testing. They re self-contained, meaning you can make a mess of them without impacting your day-to-day computing environment. They can run different distributions, kernels, and even entirely different operating systems from the one you use regularly. Etc. They re also cheaper than cloud services and provide finer grained control over the resources. I figured I d share a little bit about how I manage different virtual machines in case anybody finds this useful. This is what works for me, but it won t necessarily work for you, or maybe you ve already got something better. I ve found it to be easy to work with, light weight, and is easy to evolve my needs change.

Use short-lived VMs Rather than keep a long-lived development VM around that you customize over time, I recommend automating the common customizations and provisioning new VMs regularly. If I m working on reproducing a bug or testing a change prior to submitting it upstream, I ll do this work in a VM and delete the VM when when I m done. When provisioning VMs this frequently, though, walking through the installation process for every new VM is tedious and a waste of time. Since most of my work is done in Debian, so I start with images generated daily by the cloud team. These images are available for multiple releases and architectures. The nocloud variant boots to a root prompt and can be useful directly, or the generic images can be used for cloud-init based customization.

Automating image preparation This makefile lets me do something like make image and get a new qcow2 image with the latest build of a given Debian release (sid by default, with others available by specifying DIST).
DATESTAMP=$(shell date +"%Y-%m-%d")
FLAVOR?=generic
ARCH?=$(shell dpkg --print-architecture)
DIST?=sid
RELEASE=$(DIST)
URL_PATH=https://cloud.debian.org/images/cloud/$(DIST)/daily/latest/
ifeq ($(DIST),trixie)
RELEASE=13
endif
ifeq ($(DIST),bookworm)
RELEASE=12
endif
ifeq ($(DIST),bullseye)
RELEASE=11
endif
debian-$(DIST)-$(FLAVOR)-$(ARCH)-daily.tar.xz:
curl --fail --connect-timeout 20 -LO \
$(URL_PATH)/debian-$(RELEASE)-$(FLAVOR)-$(ARCH)-daily.tar.xz
$(DIST)-$(FLAVOR)-$(DATESTAMP).qcow2: debian-$(RELEASE)-$(FLAVOR)-$(ARCH)-daily.tar.xz
tar xvf debian-$(RELEASE)-$(FLAVOR)-$(ARCH)-daily.tar.xz
qemu-img convert -O qcow2 disk.raw $@
rm -f disk.raw
qemu-img resize $@ 20g
qemu-img snapshot -c untouched $@
image: $(DIST)-$(FLAVOR)-$(DATESTAMP).qcow2
.PHONY: image

Customize the VM environment with cloud-init While the nocloud images can be useful, I typically find that I want to apply the same modifications to each new VM I launch, and they don t provide facilities for automating this. The generic images, on the other hand, run cloud-init by default. Using cloud-init, I can create my user account, point apt at local mirrors, install my preferred tools, ensure the root filesystem is resized to make full use of the backing storage, etc. The cloud-init configuration on the generic images will read from a local config drive, which can contain an ISO9660 (cdrom) filesystem image. This image can be generated from a subdirectory containing the various cloud-init input files using the following make syntax:
IMDS_FILES=$(shell find seedconfig -path '*/.git/*' \
-prune -o -type f -name '*.in.json' -print) \
seedconfig/openstack/latest/user_data
seed.iso: $(IMDS_FILES)
genisoimage -V config-2 -o $@ -J -R -m '*~' -m '.git' seedconfig
With the image in place, the VM can be created with
 qemu-system-x86_64 -machine q35,accel=kvm
-cpu host -m 4g -drive file=$ img ,index=0,if=virtio,media=disk
-drive file=seed.iso,media=cdrom,format=raw,index=2,if=virtio
-nic user -nographic
This invokes qemu with the root volume and ISO image attached as disks, uses an emulated q35 machine with the host s CPU and KVM acceleration, the userspace network stack, and a serial console. The first time the VM boots, cloud-init will apply the configuration from the cloud-config available in the ISO9660 filesystem.

Alternatives to cloud-init virt-customize is another tool accomplishing the same type of customization. I use cloud-init because it works directly with cloud providers in addition to local VM images. You could also use something like ansible.

Variations I have a variant of this that uses a bridged network, which I ll write more about later. The bridge is nice because it s more featureful, with full support for IPv6, etc, but it needs a bit more infrastructure in place. It also can be helpful to use 9p or virtfs to share filesystem state between the host the VM. I don t tend to rely on these, and will instead use rsync or TRAMP for moving files around. Containers are also useful, of course, and there are plenty of times when the full isolation of a VM is not worth the overhead.

19 December 2024

Gregory Colpart: MiniDebConf Toulouse 2024

After the MiniDebConf Marseille 2019, COVID-19 made it impossible or difficult to organize new MiniDebConfs for a few years. With the gradual resumption of in-person events (like FOSDEM, DebConf, etc.), the idea emerged to host another MiniDebConf in France, but with a lighter organizational load. In 2023, we decided to reach out to the organizers of Capitole du Libre to repeat the experience of 2017: hosting a MiniDebConf alongside their annual event in Toulouse in November. However, our request came too late for 2023. After discussions with Capitole du Libre in November 2023 in Toulouse and again in February 2024 in Brussels, we confirmed that a MiniDebConf Toulouse would take place in November 2024! We then assembled a small organizing team and got to work: a Call for Papers in May 2024, adding a two-day MiniDebCamp, coordinating with the DebConf video team, securing sponsors, creating a logo, ordering T-shirts and stickers, planning the schedule, and managing registrations. Even with lighter logistics (conference rooms, badges, and catering during the weekend were handled by Capitole du Libre), there was still quite a bit of preparation to do. On Thursday, November 14, and Friday, November 15, 2024, about forty developers arrived from around the world (France, Spain, Italy, Switzerland, Germany, England, Brazil, Uruguay, India, Brest, Marseille ) to spend two days at the MiniDebCamp in the beautiful collaborative spaces of Artilect in Toulouse city center.
Then, on Saturday, November 16, and Sunday, November 17, 2024, the MiniDebConf took place at ENSEEIHT as part of the Capitole du Libre event. The conference kicked off on Saturday morning with an opening session by J r my Lecour, which included a tribute to Lunar (Nicolas Dandrimont). This was followed by Reproducible Builds Rebuilding What is Distributed from ftp.debian.org (Holger Levsen) and Discussion on My Research Work on Sustainability of Debian OS (Eda). After lunch at the Capitole du Libre food trucks, the intense afternoon schedule began: What s New in the Linux Kernel (and What s Missing in Debian) (Ben Hutchings), Linux Live Patching in Debian (Santiago Ruano Rinc n), Trixie on Mobile: Are We There Yet? (Arnaud Ferraris), PostgreSQL Container Groups, aka cgroups Down the Road (C dric Villemain), Upgrading a Thousand Debian Hosts in Less Than an Hour (J r my Lecour and myself), and Using Debusine to Automate Your QA (Stefano Rivera & co). Sunday marked the second day, starting with a presentation on DebConf 25 (Benjamin Somers), which will be held in Brest in July 2025. The morning continued with talks: How LTS Goes Beyond LTS (Santiago Ruano Rinc n & Roberto C. S nchez), Cross-Building (Helmut Grohne), and State of JavaScript (Bastien Roucari s). In the afternoon, there were Lightning Talks, PyPI Security: Past, Present & Future (Salvo LtWorf Tomaselli), and the classic Bits from DPL (Andreas Tille), before closing with the final session led by Pierre-Elliott B cue. All talks are available on video (a huge thanks to the amazing DebConf video team), and many thanks to our sponsors (Viridien, Freexian, Evolix, Collabora, and Data Bene). A big thank-you as well to the entire Capitole du Libre team for hosting and supporting us see you in Brest in July 2025! Articles about (or mentioning) MiniDebConf Toulouse:

17 December 2024

Russ Allbery: Review: Iris Kelly Doesn't Date

Review: Iris Kelly Doesn't Date, by Ashley Herring Blake
Series: Bright Falls #3
Publisher: Berkley Romance
Copyright: October 2023
ISBN: 0-593-55058-7
Format: Kindle
Pages: 381
Iris Kelly Doesn't Date is a sapphic romance novel (probably a romantic comedy, although I'm bad at romance subgenres). It is the third book in the Bright Falls series. In the romance style, it has a new set of protagonists, but the protagonists of the previous books appear as supporting characters and reading this will spoil the previous books. Among the friend group we were introduced to in Delilah Green Doesn't Care, Iris was the irrepressible loudmouth. She's bad at secrets, good at saying whatever is on her mind, and has zero desire to either get married or have children. After one of the side plots of Astrid Parker Doesn't Fail, she has sworn off dating entirely. Iris is also now a romance novelist. Her paper store didn't get enough foot traffic to justify staying open, so she switched her planner business to online only and wrote a romance novel that was good enough to get a two-book deal. Now she needs to write a second book and she has absolutely nothing. Her own avoidance of romantic situations is not helping, but neither is her meddling family who are convinced her choices about marriage and family can be overturned with sufficient pestering. She desperately needs to shake up her life, get out of her creative rut, and do something new. Failing that, she'll settle for meeting someone in a bar and having some fun. Stevie is a barista and actress living in Portland. Six months ago, she broke up with Adri, her creative partner, girlfriend of six years, and the first person with whom she had a serious relationship. More precisely, Adri broke up with her. They're still friends, truly, even though that friendship is being seriously strained by Adri dating Vanessa, another member of their small and close-knit friend group. Stevie has occasionally-crippling anxiety, not much luck in finding real acting roles in Portland, and a desperate desire to not make waves. Ren, the fourth member of their friend group, thinks Stevie needs a new relationship, or at least a fling. That's how Stevie, with Ren as backup and encouragement, ends up at the same bar with Iris. The resulting dance and conversation was rather fun for both Stevie and Iris. The attempted one-night stand afterwards was a disaster due to Stevie's anxiety, and neither of them expected to see the other again. Stevie therefore felt safe pretending they'd hit it off to get her friends off her back. When Iris's continued restlessness lands her in an audition for Adri's fundraiser play that she also talked Stevie into performing in, this turns into a full-blown fake dating trope. These books continue to be impossible to put down. I'm not sure what Blake is doing to make the pacing so perfect, but as with the previous books of the series I found this utterly compulsive reading. I started it in the afternoon, took a break in the evening for a few hours, and then finished it at 2am. I wasn't sure if a book focused on Iris would work as well, but I need not have worried. Iris Kelly Doesn't Date is both more dramatic and more trope-centered than the earlier books, but Blake handles that in a way that fits Iris's personality and wasn't annoying even to a reader like me, who has an aversion to many types of relationship drama. The secret is Stevie, and specifically having the other protagonist be someone with severe anxiety.
No was never a very easy word for Stevie when it came to Adri, when it came to anyone, really. She could handle the little stuff do you want a soda, have you seen this movie, do you like onions on your pizza but the big stuff, the stuff that caused disappointed expressions and down-turned mouths... yeah, she sucked at that part. Her anxiety would flare, and she'd spend the next week convinced her friends hated her, she'd die alone and miserable, and wasn't worth a damn to anyone. Then, when said friend or family member eventually got ahold of her to tell her that, no, of course they didn't hate her, why in the world would she think that, her anxiety would crest once again, convincing her that she was terrible at understanding people and could never trust her own brain to make heads or tails of any social situation.
This is a spot-on description of a particular type of anxiety, but also this is the perfect protagonist to pair with Iris. Throughout the series, Iris has always been the ride-or-die friend, the person who may have no idea how to help but who will show up anyway and at least try to distract you. Stevie's anxiety makes Iris feel protective, which reveals one of the best sides of Iris's personality, and then the protectiveness plays off against Iris's own relationship issues and tendency to avoid taking anything too seriously. It's one of those relationships that starts a bit one-sided and then becomes mutually supporting once Stevie gets her feet under her. That's a relationship pattern I really enjoy reading about. As with the rest of the series, the friendship dynamics are great. Here we get to see two friend groups at work: Iris's, which we've seen in the previous two volumes and which expanded interestingly in Astrid Parker Doesn't Fail, and Stevie's, which is new. I liked all of these people, even Adri in her own way (although she's the hardest to like). The previous happily-ever-afters do get a bit awkward here, but Blake tries to make that part of the plot and also avoids most of the problem of somewhat-boring romantic bliss by spreading the friendship connections a bit wider. Stevie's friend group formed at orientation at Reed College, and that let me put my finger on another property of this series: essentially all of the characters are from a very specific social class. They're nearly all arts people (bookstore owner, photographer, interior decorator, actress, writer, director), they've mostly gone to college, and while most of them don't have lots of money, there's always at least one person in each friend group with significant wealth. Jordan, from the previous book, is a bit of an exception since she works in a trade (a carpenter), but she still acts like someone from that same social class. It's a bit like reading Jane Austen novels and realizing that the protagonists are drawn from a very specific and very narrow portion of society. This is not a complaint, to be clear; I have no objections to reading about a very specific social class. But if one has already read lots of books about this class of people, I could see that diminishing the appeal of this series a bit. There are a lot of assumptions baked into the story that aren't really questioned, such as the ubiquity of therapists. (I don't know how Stevie affords one on a barista salary.) There are also some small things in the terminology (therapy speak, for example) and in the specific type of earnestness with which the books attempt to be diverse on most axes other than social class that I suspect may grate a bit for some readers. If that's you, this is your warning. There is a third-act breakup here, just like the previous volumes. There is also a defense of the emotional punch of third-act breakups in romance novels in the book itself, put into Iris's internal monologue, so I suspect that's the author's answer to critics like myself who don't like the trope. I was less frustrated by this one because it fit the drama level of the protagonists, but I'll also know to expect a third-act breakup in any Blake novel I read in the future. But, all that said, the summary once again is that I loved this book and could not put it down. Iris is dramatic and occasionally self-destructive but has a core of earnest empathy that makes her easy to like. She's exactly the sort of extrovert who is soothing to introverts rather than draining because she carries the extrovert load of social situations. Stevie is adorably earnest and thoughtful beneath her anxiety. They two of them are wildly different and yet remarkably good together, and I loved reading their story. Highly recommended, along with the whole series. Start with Delilah Green Doesn't Care; if you like that, you're in for a treat. Content note: This book is also rather sex-forward and pretty explicit in the sex scenes, maybe a touch more than Astrid Parker Doesn't Fail. If that is or is not your thing in romance novels, be aware going in. Rating: 9 out of 10

16 December 2024

Russ Allbery: Review: Finders

Review: Finders, by Melissa Scott
Series: Firstborn, Lastborn #1
Publisher: Candlemark & Gleam
Copyright: 2018
ISBN: 1-936460-87-4
Format: Kindle
Pages: 409
Finders is a far future science fiction novel with cyberpunk vibes. It is the first of a series, but the second (and, so far, only other) book of the series is a prequel. It stands alone reasonably well (more on that later). Cassilde Sam is a salvor. That means she specializes in exploring ancient wrecks and ruins left behind by the Ancients and salvaging materials that can be reused. The most important of those are what are called Ancestral elements: BLUE, which can hold programming; GOLD, which which reacts to BLUE instructions; RED, which produces actions or output; and GREEN, the rarest and most valuable, which powers everything else. Cassilde and her partner Dai Winter file claims on newly-discovered or incompletely salvaged Ancestor sites and then extract elemental material and anything else of value in their small salvage ship. Cassilde is also dying. She has Lightman's, an incurable degenerative disease that can only be treated with ever-increasing quantities of GREEN. It's hard to sleep, hard to get warm, hard to breathe, and eventually she'll run out of money to pay for the GREEN and she'll die. To push that day off into the future, she and Dai need work. The good news is that the wreckage of a new Ancestor sky palace was discovered in a long orbit and will create enough salvage work for every experienced salvor in the system. The bad news is that they're not qualified to bid on it. They need a scholar with a class-one license to bid on the best sections, and they haven't had a reliable scholar since their former partner and lover Summerland Ashe picked the opposite side in the Troubles and left the Fringe for the Entente, the more densely settled and connected portion of human space. But, unexpectedly and suspiciously, Ashe may be back and offering to work with them again. So, first, I love this setting. This is far from the first SF novel that is set in the aftermath of a general collapse of human civilization and revolving around discovering lost mysteries. Most examples of that genre are post-apocalyptic novels limited to Earth or the local solar system, but Kate Elliott's Unconquerable Sun comes immediately to mind. It's also not the first space archaeology series I've read; Kristine Kathyrn Rusch's story series starting with "Diving into the Wreck" also came to mind. But I don't recall the last time I've seen the author sell the setting so effectively. This is a world with starships and spaceports and clearly advanced technology, but it feels like a post-collapse society that's built on ruins. It's not just that technology runs on half-understood Ancestral elements and states fight over control of debris fields. It's also that the society repurposes Ancestral remnants in ways that both they and the reader know weren't originally intended, and that sometimes are more ingenious or efficient than how the Ancestors probably used them. There's a creative grittiness here that reminds me of good cyberpunk. It's not just good atmospheric writing, though. Scott makes a world-building decision that is going to sound trivial when I say it, but that has brilliant implications for the rest of the setting. There was not just one collapse; there were two. The Ancestor civilization, presumed to be the first human civilization, has passed into myth, quite literally when it comes to the stories around its downfall in the aftermath of a war against AIs. After the Ancestors came the Successors, who followed a similar salvage and rebuild approach and got as far as inventing their own warp drive technology that was based on but different than the Ancestor technology. Then they also collapsed, leaving their adapted technology and salvage operations layered over Ancestor sites. Cassilde's civilization is the third human starfaring civilization, and it is very specifically the third, neither the second nor one of dozens. This has so many small but effective implications that improve this story. A fall happened twice, so it feels like a pattern that makes Cassilde's civilization paranoid, but it happened for two very different reasons, so there is room to argue against it being a pattern. Salvage is harder because of the layering of Ancestor and Successor activity. Successors had their own way of controlling technology that is not accessible to Cassilde and her crew but is also not how the technology was intended to be used, which sends small ripples of interesting complexity through the background. And salvors are competing not only against each other but also against Successor salvage operations for which they have fragmentary records. It's a beautifully effective touch. Melissa Scott has been publishing science fiction for forty years, and it shows in this book. The protagonists are older characters: established professionals with resource problems but also social connections and an earned reputation, people who are trying to do a job and live their lives, not change the world. The writing is competent, deft, and atmospheric, with the confidence of long practice, but it also has the feel of an earlier era of science fiction. I mentioned the cyberpunk influence, which shows in the grittiness of the descriptions, the marginality of the characters in society, and the background theme of repurposing and reusing technology in unintended ways. This is the sort of book that feels solidly in the center of science fiction, without the genre mixing into either fantasy or romance that has become somewhat more common, and also without the dramatics of space opera (although the reader discovers that the stakes of this novel may be higher than anyone realized). And yet, so much of this book is about navigating a complicated romantic relationship, and that's where the story structure felt a bit odd. Cassilde, Dai, and Ashe were a polyamorous triad (polyamory also shows up in Scott's excellent Roads of Heaven series), and much of the first third of the book deals with the fracturing of trust with Ashe and their renegotiation of that relationship given his return. This is refreshingly written as the thoughtful interaction of three adults who take issues of trust seriously, but that also means it's much less dramatic than it sounds, and that means this book starts exceptionally slow. Scott is going somewhere, and the slow build became engrossing around the midpoint of the book, but I had to fight to stick with it at the start. About 80% of the way through this book, I had no idea how Scott was going to wrap things up in the pages remaining and was bracing myself for some sort of series cliffhanger. This is not what happens; the plot is not fully resolved in every detail, but it reaches a conclusion of sorts that does not mandate a sequel. I did think the end was a little bit unsatisfying, though, and I want another book that explores the implications of the ending. I think it would have to be a much different book, and the tonal shift might be stark. I've had this book on my to-read list for a while and kept putting it off because I wasn't sure I was in the mood for something precarious and gritty. This turned out to be an accurate worry: this is literally a book about salvaging the pieces of something full of wonders inextricably connected to dangers. You have to be in a cyberpunk sort of mood. But I've never read a bad Melissa Scott book, and this is no exception. The simplicity and ALL-CAPSNESS of the Ancestral elements grated a bit, but apart from that, the world-building is exceptional and well worth the trip. Recommended, although be warned that, if you're like me, it may not grab you from the first page. Followed by Fallen, but that book is a prequel that does not share any protagonists. Content notes: disability and degenerative illness in a universe where magical cures are possible, so be warned if that specific thematic combination is not what you're looking for. Rating: 7 out of 10

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